Environmental Microbiology of Aquatic and Waste Systems

238 9 Municipal Purification of Water

Contaminant MCLGa (mg/L)b

MCL or TTa

(mg/L)b

Potential health effects from

ingestion of water

Sources of contaminant in
drinking water
Fluoride 4.0 4.0 Bone disease (pain and
tenderness of the bones);
Children may get mottled teeth

Water additive, which
promotes strong teeth;
erosion of natural deposits;
discharge from fertilizer
and aluminum factories
Lead Zero TTh; action
level = 0.015

Infants and children: Delays in

physical or mental develop-

ment; children could show

slight deficits in attention span

and learning abilitiesAdults:

Kidney problems; high blood

pressure

Corrosion of household

plumbing systems; erosion

of natural deposits

Mercury (inorganic) 0.002 0.002 Kidney damage Erosion of natural deposits;
discharge from refineries
and factories; runoff from
landfills and croplands
Nitrate (measured as
nitrogen)

10 10 Infants below the age of

6 months who drink water

containing nitrate in excess of

the MCL could become

seriously ill and, if untreated,

may die. Symptoms include

shortness of breath and

blue-baby syndrome.

Runoff from fertilizer use;

leaching from septic tanks,

sewage; erosion of natural

deposits

Nitrite (measured as
nitrogen)

1 1 Infants below the age of

6 months who drink water

containing nitrite in excess of

the MCL could become

seriously ill and, if untreated,

may die. Symptoms include

shortness of breath and

blue-baby syndrome.

Runoff from fertilizer use;

leaching from septic tanks,

sewage; erosion of natural

deposits

Selenium 0.05 0.05 Hair or fingernail loss;
numbness in fingers or toes;
circulatory problems

Discharge from petroleum
refineries; erosion of
natural deposits; discharge
from mines
Thallium 0.0005 0.002 Hair loss; changes in blood;
kidney, intestine, or liver
problems

Leaching from ore-pro-

cessing sites; discharge

from electronics, glass, and

drug factories

Contaminant MCLGa (mg/L)b

MCL or TTa

(mg/L)b

Potential health effects from

ingestion of water

Sources of contaminant in
drinking water
Organic chemicals
Acrylamide Zero TTi Nervous system or blood
problems; increased risk of
cancer

Added to water during
sewage/wastewater
treatment
Alachlor Zero 0.002 Eye, liver, kidney, or spleen
problems; anemia; increased
risk of cancer

Runoff from herbicide

used on row crops

Atrazine 0.003 0.003 Cardiovascular system or
reproductive problems

Runoff from herbicide
used on row crops
Benzene Zero 0.005 Anemia; decrease in blood
platelets; increased risk of
cancer

Discharge from factories;

leaching from gas storage

tanks and landfills

(continued)

Table 9.5 (continued)